The invention relates to the new and distinct hibiscus plant ‘15734-1 GR’. ‘15734-1 GR’ was generated from a cross performed on Jul. 12, 2014 near Vernon, Tex. between ‘12078-5’ (pod parent, unpatented) and ‘14188-2W’ (pollen parent, unpatented). The pedigrees of each parent reflect a complex mixture of hibiscus species that include, for example, H. mocheutos, H. coccineus, H. militaris, or H. dasycalyx. The seed from this cross was harvested on Aug. 30, 2014 and the ‘15734-1 GR’ seedling was selected in the summer of 2015. ‘15734-1 GR’ was first asexually propagated near Vernon, Tex. in 2016 by stem tip cuttings. The resulting as well as subsequent asexually propagated plants have been stable and true to type throughout successive generations.